Method and apparatus for heat resistant coatings

ABSTRACT

A blister pack includes a housing having a plurality of cavities and a cover sealed to the housing and enclosing the cavities. The cover including a base layer, at least one security element, and a heat protective layer. The heat protective layer includes one of an amorphous polymer and a semi-crystalline polymer.

FIELD OF THE INVENTION

The present invention relates, generally, to heat resistant coatings,and more particularly, to heat resistant coatings and films for theprotection of security elements as imprinted on, or adhered to, asubstrate.

BACKGROUND OF THE INVENTION

Coatings, i.e., films, are widely used as physical barriers to sealitems into their packaging. Often, they are known as “lidding films”,such as when used in connection with blister packs in the packaging ofpharmaceutical medicaments. As is understood by those of ordinary skill,the presence of the film serves to provide a physical barrier to theegress of, e.g., the medicament from the individual blister cavities inthe aforementioned blister pack. Puncturing of the physical film istherefore required before any of the product housed within the closedcavities may be dispensed. Such a physical barrier not only securelyholds the product against undesired egress, but also provides a measureof tamper-evident security protection, as an intended user may observeany deterioration of the physical barrier and know thereby thattampering or damage may have affect the sealed product.

Beyond concerns over the physical integrity of the packaging asaccomplished by the lidding/sealing barrier, additional variousmechanisms have been created so as to give a visual indication of, e.g.,the source of the packaged goods, and/or the unadulterated condition ofthe goods themselves. Thus, in certain industries, such as thepharmaceutical or electronics industries, security insignia and othervisual markings are often imprinted or deposited onto the physicalbarrier/film to serve as an indication of whether, e.g., the drugscontained in a blister pack are authentic and unadulterated. To this enda number of security elements designed to deter would-be counterfeitersmay be incorporated into, or deposited upon, the film. One such knownsecurity deposition are holographic or other fine-structured imagery orelements. As will therefore be appreciated, a premium is placed onmaintaining the integrity of the security elements.

Problems exist, however, for packaging that utilizes, e.g., holographicor other deposited and/or imprinted security elements, in that theseelements are often distorted or otherwise damaged during the heatsealing process that is integral to many packaging procedures. That is,in many known packaging systems that utilize a lidding or physicalbarrier, e.g., medicament blister packs, the progenitor physicalbarrier/film is first imprinted or deposited with various securityelements, e.g., holographic elements, before the imprinted film isthereafter sealed to the blister pack. The sealing process typicallyinvolves utilizing a heated sealing die to press upon, and thereby seal,the physical barrier/film to the packaging of the blister pack.

It has long been known that this type of sealing process may tend todestroy the integrity of any, e.g., holographic element(s) imprinted ordeposited upon the physical barrier/film, and so the relevant art isreplete with differing die structures, each having specialized cavitiesand areas of differing heat profiles, all in an effort to protect thoseareas of the physical barrier/film having security elements fromlocalized, excessive heat and the resultant degradation that wouldotherwise be incident upon these security elements during the sealingprocess.

As will be appreciated, the use of specialized sealing dies adds manylevels of complexity and expense to the manufacturing and sealingprocess.

For their part, those of ordinary skill in the deposition or imprintingof security elements, i.e., holographic elements, have long utilized aseries of various coatings and films so as to cover the depositedsecurity elements from physical degradation during manufacture andshipping. That is, security forms/elements are typically deposited orimprinted upon, e.g., a lidding sheet or other substrate when positionedon a planar platen, before being rolled up for eventual storage and/orshipping. These rolls of coated substrate can be quite large, weighingover a ton or more, and so induce a great amount of pressure upon thesurface of the coated substrate, including upon the holographic elementsthereon.

A collection of known chemical coatings/films have long been recognizedas being able to protect any deposited or imprinted forms/elements fromfrictional and pressure damage, and these coatings are typically appliedfor this purpose during the deposition stage, so as to protect thesecurity forms/elements from damage when the substrate is rolled andthereafter stored or shipped.

The present invention has recognized that some of the coatings typicallyutilized to protect security elements from damage during shipping mayalso provide sufficient heat resistance to security elements when socoated with the same.

Thus, it is a primary aspect of the present invention to propose amethod and apparatus that can effectively protect deposited or imprintedsecurity elements from damage during a heat sealing process, without theneed for structurally complex and expensive sealing dies.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, a method ofprotecting security elements deposited on a substrate from heatdegradation during a heat sealing process includes defining a securityelement on the substrate, coating the security element with a heatresistant coating formed from a semi-crystalline polymer, and sealingthe coated substrate to a package housing.

According to another embodiment of the present invention, a method ofprotecting security elements deposited on a substrate from heatdegradation during a heat sealing process includes defining a securityelement on substrate, coating the security element with a heat resistantcoating formed from a semi-crystalline polymer, defining a thickness ofthe semi-crystalline polymer in dependence upon a predetermined heatprofile to be used during the heat sealing process, and sealing thecoated substrate to a package housing with the predetermined heatprofile.

According to yet another embodiment of the present invention, blisterpack includes a housing having a plurality of cavities and a coversealed to the housing and enclosing the cavities. The cover includes abase layer, at least one security element, and a heat protective layer.The heat protective layer is comprised from one of an amorphous polymerand a semi-crystalline polymer in order to provide for heat resistanceduring the sealing of the cover to the blister pack housing.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present invention willbecome apparent on reading the detailed description below with referenceto the drawings, which are illustrative but non-limiting, wherein:

FIG. 1 is a cross-sectional view of an embodiment of a heat resistantmulti-layer film.

FIG. 2 is a flow chart illustrating a method of making a heat resistantmulti-layer film according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will be made below in detail to exemplary embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference characters usedthroughout the drawings refer to the same or like parts, withoutduplicative description.

While embodiments disclosed herein are described with respect to acoatings and films used to protect security elements integrated into thelidding material of pharmaceutical blister packs, the present inventionis not so limited in this regard. IN particular, it is contemplated thatthe inventive coatings and films may be utilized in any applicationwhere heat protection of a deposited or printed element on a substrateis desired including, but not limited to, security papers, productpackaging, lidding, and the like.

As used herein, the terms “substantially,” “generally,” and “about”indicate conditions within reasonably achievable manufacturing andassembly tolerances, relative to ideal desired conditions suitable forachieving the functional purpose of a component or assembly.

Moreover, the term “multi-layer film” or “film” refers to amulti-leveled material that usually takes the form of a sheet whenassembled. Individual layers may be of uniform material or have multiplematerials incorporated into a single layer. An individual layer may alsobe comprised of sub-layers with individual properties. Materialscomprising the various layers may be formed and bound together in anynumber of orders using any of the various techniques known in the art.Certain layers may be a continuous sheet at time of application, otherlayers may be formed by discrete deposition (e.g., sprayed on inks orpolymers, floating a liquid that then cures, etc.).

The term “primer”, as used herein, refers to a material applied to alayer in order to prepare it for a subsequent step. A primer may also bean individual layer as part of a multi-layer film, part of a layer, orin between layers. In some embodiments a primer material may serve morethan one particular function (e.g., to prepare a surface for printingwhile serving as a protective barrier). Primer material may be formed ordeposited on an adjacent surface. In certain embodiments the primer maybe a polymer sheet. In certain other embodiments the primer may besprayed on and cured.

Also, as used herein the term “blister pack” refers to a type ofpackaging wherein cavities formed in a first material are subsequentlysealed using a lidding film. A lidding film may be a multi-layer film ormay be composed of a single material.

Also, as used herein the term “security element” refers to elementsdesigned and/or configured to combat counterfeiting, thus providingassurance to the consumer that products contained in packaging sealed bythe film are genuine and unadulterated. In some embodiments thecounterfeit-deterrence measure may be a hologram. In some embodimentsthe counterfeit-deterrence measure may be microprinted words or imagesthat may also be a part of a hologram. In other embodiments an embossedpattern may be imposed over the surface of a layer. In other embodimentsa security strip may be embedded in the layer. The above examples mayappear alone or in combination with each other and other similarmeasures. A counterfeit-deterrence measure may be part of a layer orsub-layer with multiple measures alone or in combination appearing aseither an individual layer, part of a sub-layer, or in combinationsthereof.

As used herein, the term “semi-crystalline” polymer refers to a materialcomprised of a collection of polymer macromolecule chains having amorphology consisting of crystalline lamellae separated by amorphousregions. Such a material may be in the form of a sheet or otherwiseformed or deposited in place as part of a multi-layer film. Alterationsto side-chain groups and the presence or absence of plasticizing agentsmay affect the final structure and distribution of the crystallinelamellae and amorphous regions in the semi-crystalline polymer material.Semi-crystalline polymers are characterized by a glass transitiontemperature (“T_(g)”) at which the semi-crystalline polymer materialundergoes a second order transition with a concomitant change in heatcapacity. In some embodiments, at or above T_(g), significantly moreheat may be added to the polymer without a greater rise in temperature.Likewise, “amorphous” polymers have no crystalline lamellae and alsoundergo a glass transition change at a glass transition temperatureT_(g).

Turning now to FIG. 1 , a multi-layer construct 100 showing use of aheat resistant coating 103 according to one embodiment of the presentinvention, is illustrated. The multi-layer construct 100 includes a baselayer/substrate/housing 101, a security layer 102, and the heatresistant protection layer 103. As shown in FIG. 1 , the multi-layerconstruct 100 reflects a blister pack having a plurality of wells 104for retaining product 105 therein. As will be appreciated, the layersshown in FIG. 1 are not drawn to scale and sizes are exaggerated tobetter illustrate component parts. Moreover, it will also be appreciatedthat the product 105 may be anything that can be sealed in such apackage. Examples can include: pharmaceuticals, electrical components,and sterilized medical supplies, amongst others.

As will be appreciated by one of ordinary skill, the base layer 101 maybe made of any material without departing from the broader aspects ofthe present invention. Indeed, the base layer 101 may be made of paperof various weights, thicknesses, and surface finishes. In otherembodiments base layer 101 may be a metallic foil, likewise of variousweights, thicknesses, and surface finishes. In an embodiment, adhesivesmay be applied to base layer 101 in order to adhere the multi-layer filmonto a surface. The adhesives may be heat activated, optically activated(e.g., UV light cured); or configured for attachment to blister pack 104by mechanical means (e.g., “knurled” or textured together; or, flowingand freezing into textured surface crevices).

As also shown in FIG. 1 , the security layer 102 contains discreetsecurity elements 106 that are imaged, printed or otherwise depositedupon the base, or lidding, layer 101. In other embodiments, the securitylayer 102, itself, may define a security element. Regardless, and asshown in the embodiment of FIG. 1 , the security elements 106, arelocated above the opening of the wells 104, although one or moresecurity elements 106 may be placed at any location within securitylayer 102 and with respect to the wells 104, without departing from thebroader aspects of the present invention.

For its part, the heat resistant protection layer 103 is composed of asemi-crystalline polymer material, preferably having crystallinelamellae separated by amorphous regions. It is an important recognitionof the present invention that by controlling the ratio, composition, andnature of the crystalline lamellae (e.g., high turned, or tilt-angled),as compared to the amorphous regions, which thereby essentially controlsthe T_(g) of a particular polymer material. In the illustrated exampleshown in FIG. 1 , a heat-activated adhesive may be applied to theinterface between the base layer 101 and the material of the blisterpack. In other embodiments, the heat resistant protection layer 103 iscomposed of a substantially homogeneous amorphous polymer material witha T_(g).

In use, a plurality of security elements 106 are printed, impregnated orotherwise deposited upon the base layer or substrate of a package, suchas the base layer 101 of the blister pack shown in FIG. 1 . Thiscombined base layer 101 plus security elements 104 must then be sealedto the material of the blister pack. Typically, this sealing processinvolves the application of heat, to melt or otherwise cause thematerial of the combined base layer 101 and security elements 106 tobecome affixed to the material of the blister pack. It will be readilyappreciated that it is of utmost importance that the heat sealingprocess does not destroy or otherwise deform or degrade the securityelements 106, during the sealing process.

By applying heat at a temperature at or below T_(g) of the polymermaterial and above the activation temperature of the adhesive, the heatresistant protection layer 103 does not deform or transmit excess heatto security elements 106, thus preserving the structure of securityelements 106. At temperatures above T_(g) the heat capacity of thesemi-crystalline or amorphous polymer material increases, providingadditional thermal protection should any process deviations occur (e.g.,unexpected increase in temperature).

It is therefore an important aspect of the present invention that it ispossible to protect security elements formed on a substrate from thedamaging effects of a heat sealing operation through the use of the heatresistant protection layer 103, alone. In this manner, the securityelements 106 are adequately protected from the heat of the sealingprocess, all without the need for sophisticated heating dies, havingcomplex architecture and differing areas of heat conductivity, as iscurrently known and employed in the art.

In some embodiments the protection layer 103 is composed of poly(methylmethacrylate) (“PMMA”). As an example, a multi-layer construct 100 witha heat resistant protection layer 103 composed of PMMA is applied to ablister pack 104 using an application temperature range of 135-160° C.and commonly at a temperature of about 147° C. (dependent upon blisterpack material composition, adhesives (if present), and specificmulti-layer construct 100 composition). This is lower than the T_(g) of165° C. of some common formulations of PMMA. Indeed, dependent uponother co-polymers, side chain compositions, presence of plasticizers,free volume of the polymer material, etc. PMMA formulations may have aT_(g) in the range of 85-165° C. Thus, in practice, a protective filmmay be formed from polymer materials chosen to have a T_(g) above theapplication temperature range. Other suitable, commercially availablepolymers can include, but are not limited to: CF7157 from Amcor; CF92997CABNC; CF5317 UTR; CF90147 Enhanced UTR; CF7427 HTNH.

The heat resistant protection layer 103 may further serve and beconfigured as a primer enabling the deposition of inks or othermaterials. Thus, in some embodiments, inks may be “overprinted” on topof the protection layer 103. As will also be appreciated, the protectionlayer 103 may be the final layer in the multi-layer film, or it may bebeneath or between one or more layers. In some embodiments, theprotection layer 103 may vary in thickness with thicker or thinner areascorresponding to areas needing more or less protection. In someembodiments the protection layer 103 may contain an embossed design thatalso serves as a counterfeit deterrence measure on its own or as part ofsecurity elements 106. In still other embodiments, as shown in FIG. 1A,protection layer 103 may contain two or more polymer materials 107, 108,with two or more T_(g)s. The two or more polymer materials may be indiscrete patches or may be continuous and/or contiguous with each otherwith either blended transitions between polymer materials or definedtransitions.

In an embodiment, the heat resistant protection layer 103 may bedeposited directly atop the base layer 101 or the security layer 102(with security elements 106) through the use of a spray applicator orliquid coating. In other embodiments, it is envisioned that theprotective layer 103 may be applied using a transfer film and/or atransfer lamination process.

Thus, the heat resistant protection layer 103 serves as a protectiveenergy shield and/or heat sink. For example, the protection layer 103acts as a heat sink that prevents the transmission of heat energy, or asa shield to other activating energies (i.e., UV, microwave, optical, IR,chemical activators, etc.) to the security elements 106 thus protectingthe counterfeit-deterrence properties to an extent that the integrity ofthe security elements 106 will not be compromised (e.g., distort,degrade, break, alter color, alter texture, etc.). In some embodiments,the protective layer 103 may serve as both a heat sink and as a shieldagainst other activation energies, for example, UV light.

Therefore, in those embodiments that use heat as the activation energy,the protection provided by protection layer 103 eliminates the need forspecially configuring the heating/sealing plate/platen of the blisterpack packaging system. Indeed, the protective layer enables the use ofstandard, flat, heating plates to seal the lidding film to withintegrated security elements 106 onto a blister pack (such as shown incut-away, in FIG. 1 ) without degrading such security elements. Themanufacturing process is therefore substantially simplified, renderingit much more cost effective.

Turning now to FIG. 2 , a method 200 of manufacturing a multi-layer film100 having a protection layer 103 is illustrated. In a first step 201, abase layer 101 is provided. In a second step 202, a security layer 102with a plurality of security elements 106 is formed or deposited on topof a base layer 101. In a third step 203, the protection layer 103 isformed or deposited on top of security layer 102. Optionally, protectionlayer 103 may also be formed on top of base layer 101, sandwichinganti-counterfeit layer 102 between two protective layers. In an optionalfourth step 204, an additional layer of ink or other material may bedeposited on top of the protection layer 103.

With further reference to FIG. 2 , additional steps may be employeddepending on the end use for the film. For example, when using the filmas a lidding material for a blister pack, in a fifth step 205, themulti-layer film 100 may be placed over the blister pack. In practice,this may be accomplished by unspooling/unwinding the multi-layer film100 from a roll and placing it in close proximity to a blister packsheet 104 with wells 104 containing product 105. As a sixth step 206,the multi-layer film 100 with security elements 106 may be aligned overthe blister pack shown in FIG. 1 in such a fashion so that securityelements 106 are aligned with wells 104. Finally, an activation energy(heat, UV rays, microwaves, mechanical pressure, etc.), such as heatapplied from a heating plate/platen, is applied as a seventh step 207sealing the multi-layer construct 100 to blister pack.

It is further to be understood that the above description is intended tobe illustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. Additionally, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from its scope.

In contrast to existing systems/methods, the protective layer andmulti-layer film disclosed herein allows for the use of securityelements in blister packs and other applications without the need forcustomized tooling, molds, or manufacturing devices (such as specializedheating plates). This decreases the overhead required to start amanufacturing process and increases the overall utility of a multi-layerfilm incorporating the protective layer.

Finally, the written description uses examples to disclose theinvention, including the best mode, and also to enable any personskilled in the art to practice the invention, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of the claims if theyhave structural elements that do not differ from the literal language ofthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.

Since certain changes may be made in the above-described invention,without departing from the spirit and scope of the invention hereininvolved, it is intended that all of the subject matter of the abovedescription shown in the accompanying drawings shall be interpretedmerely as examples illustrating the inventive concept herein and shallnot be construed as limiting the invention.

What is claimed is:
 1. A method of protecting security elementsdeposited on a substrate from heat degradation during a heat sealingprocess, said method comprising the steps of: providing a securityelement on said substrate, wherein the security element is at least oneof: an embossed hologram, microprinted words or images, an embossedpattern and a security strip, wherein said substrate is made of paper ormetallic foil and said security element and said substrate arecoextensive; applying a heat resistant coating directly over and incontact with said security element after said step of providing saidsecurity element on said substrate, said heat resistant coating beingformed from a semi-crystalline polymer having a glass transitiontemperature in the range of 85° C. to about 165° C.; providing anadhesive layer on said substrate opposite said security element; andwith said heat resistant coating atop said security element, and saidadhesive layer on said substrate opposite said security element, sealingsaid substrate to a package housing.
 2. The method according to claim 1,wherein: said security element is an embossed hologram.
 3. The methodaccording to claim 2, wherein: said sealing is accomplished with a die,said die having a substantially uniform heating profile.
 4. The methodaccording to claim 1, further comprising the step of: prior to providingsaid security element on said substrate, applying a second heatresistant coating on top of said substrate to which said securityelement will be provided so that said security element is sandwichedbetween the heat resistant coating and the second heat resistantcoating.
 5. The method according to claim 1, wherein: the heat resistantcoating includes two or more polymer materials each having a differentglass transition temperature.
 6. The method according to claim 1,wherein: the heat resistant coating is PMMA.
 7. A method of protectingsecurity elements deposited on a substrate from heat degradation duringa heat sealing process, said method comprising the steps of: defining asecurity element on said substrate, wherein the security element is atleast one of: an embossed hologram, microprinted words or images, anembossed pattern and a security strip, wherein said substrate is made ofpaper or metallic foil and said security element and said substrate arecoextensive; applying a heat resistant coating atop said securityelement, said heat resistant coating being formed from asemi-crystalline polymer having a glass transition temperature in therange of 85° C. to about 165° C.; providing an adhesive layer on saidsubstrate opposite said security element; and with said heat resistantcoating atop said security element, and said adhesive layer on saidsubstrate opposite said security element, sealing said substrate to ablister pack such that said heat resistant coating inhibits degradationof said security element due to heat.
 8. The method according to claim7, wherein: said security element is an embossed hologram.
 9. The methodaccording to claim 8, wherein: said sealing is accomplished with a die,said die having a substantially uniform heating profile.
 10. The methodof claim 7, wherein said heat resistant coating provides additionalthermal protection if process deviations or unexpected increases intemperature occur.
 11. A method of forming a multi-layer film,comprising: providing a base layer made up of paper or metallic foil;applying a security layer atop said base layer, said security layerhaving at least one security element, wherein the security element is atleast one of: an embossed hologram, microprinted words or images, anembossed pattern and a security strip, wherein said security layer andsaid base layer are coextensive; applying a protection layer atop saidsecurity layer after applying the security layer atop the base layer;and providing an adhesive layer on said base layer opposite saidsecurity layer, wherein said protection layer is a quasi-crystallinepolymer material having a glass transition temperature in the range of85° C. to about 165° C.; and wherein said protection layer forms apermanent part of said multi-layer film and is configured to insulatesaid at least one security element from heat during application of saidmulti-layer film to a blister pack using a heat sealing process.
 12. Themethod of claim 11, wherein the security element is an embossedhologram.
 13. The method of claim 11, further comprising: placing themulti-layer film over the blister pack; aligning at least one securityelement over at least one well of the blister pack; and, applying anactivation energy.
 14. The method of claim 13 further comprising:applying an additional layer.
 15. The method of claim 11, wherein saidprotection layer is applied using a transfer film and transferlamination process.